Light signal



May 13, 1930.

c. s SNAVELY LIGHT SIGNAL Filed Oct 19, 1923 '2 Sheets-Sheet 1INVENTOR'.

c. s. SNAVELY May 13, 1930.

LIGHT SIGNAL Filed Oct. 19/ 1925 2 Sheets-Sheet INVENTOR'.

Patented May 13, 1930 UNITED STATES PATENT OFFICE i CLARENCE S. SNAVELY,OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TOTHE UNION swr'rcn & SIGNALCOMPANY, or SWISSVALE, PENNSYLVANIA, A conrozaArroN or PENNSYLVANIALIGHT sreNAL Application filed October 19, 1923. Serial No. 669,488."

My invention relates to light signals, and is' particularly adapted forsignals of this type used in railway trafiic controlling systems. 1 p

I will describe one form of light signal embodying my invention, andwill then point out the noval features thereof in claim.

In the accompanying drawings, Fig. 1 is a view showing in frontelevation one form of light signal embodying my invention. Fig; 2 is arear view of the signal shown in Fig. 1. Fig. 3 is a vertical sectionalview along the line TIL-III of Fig. 2. Fig. 4e is a horizontal sectionalview on the line IV-IV of Fig. 3, looking in the direction of thearrows. Fig. 5 is a detail view showing, in elevation, the back lightreflector for the signal illustrated in the first four views. Fig. 6 isa detail view showing the bacl 4 light housing as viewed from the rightin Fig. 2.

Similar reference characters refer to similar parts in each of theseveral views.

Referring first to Figs. 1, Zand 3 the signal comprises a triangularfront plate 1. The front plate 1 is provided at its top with a yoke 1,and at its bottom with two lugs 1", by means of which the signal may beadjustably mounted in any desired manner. Three light units R, Y and Gare attached to plate 1 by means of bolts 4. These light units are somounted that their centers are at the vertices of a triangle of whichone vertex is di- I rected downwardly. Each light unit is containedjn ashell designated by the reference character 2 with an-exponentcorresponding to the unit, and a cover designated by the 7 referencecharacter 3 also with a suitable exponent. These shells 2 are integralwith front plate 1.

- The front plate 1 is provided with three apertures one immediately infront of each light unit. Each aperture is provided with a lensstructure forming part of the light unit and which, as here showncomprises a front lens and a back lens designated by the referencecharacters 11 and 12,'respectively, with exponents corresponding to theunits. These lens structures are supported in a suitable frame 15 whichis supported on plate 1 by bolts 1. Behin car-b lens structure is anrespective shells 2.

nal and passing through electric lamp, designated by thereferencecharacter 13, and also forming part of the light unit, the filament ofthis lamp being- I located at the focus of the associated lenscombination. Each front lens 11 is protected from snow and from thedirect rays of'the sun by means of a hood 14 of suitable shape supportedby the front plate 1.- In addition to the lamp 13, light unit R containsa terminal board C comprising binding posts 14 which are connected withthe lamps 13 of the.

various units. v I I 7 Supported by front plate 1 and located in thecenter of the triangle defined by the three light units is a pin whichprojects towards the back ot the signal and which terminates in athreaded tip 5. A- Y-shapedspider B i is provided with a hole at itscenter to. ac-

commodate the pin 5. Each of the covers 3 is attached, by means of arivet 6 to the'end of one leg of the spider B. It will be noticed thatwith this method of connection, relative I movement of any cover withrespect to any other cover is impossible. A nut 8 is threaded on the tip5 of pin 5 to force the spider B to the right as viewed-in Fig. 3 thusclamping the cove-rs 3 against the edges of their with a hasp 9 arrangedto latch over a staple 10 in the lower leg of spider B. The staple 10 isprovided with a hole 10' to receive the yoke of a padlock by means ofwhich the covers may be locked in position since it is obvious that ifnut 8 is screwed up and locked in position the. covers cannot beremoved. Since the covers are thus rigidly fastened together by .meansof spider B it is plain that no one'cover can be moved away from itsassociated shell without also removing the other covers from theirshells.

Since no one cover 3 can be removed without also removing the other twocovers, there is no possibility of a false indication due to transmittedlight originating behind the sigone of the colored lenses '11. That isto say, in the event of such a light behind the signal and one of theunits being open, the remaining unlts would also The nut 8 is providedbe open and all three lens structures would be equally illuminated.

In order to accommodate the terminal board C the 'shell 2 is larger thanshells 2 and 2", and cover 3 is therefore larger than cover 3 and 3". Itfollows that the larger 5 mass of cover 3 biases this cover to theposition shown in the drawing and hence all covers normally occupypositionsimmediately behind their respective units. 7

Means are provided for imparting a dis- 1g tinctive' color to thebeam'of light projected from each light unit. This may be done by givina distinctive 'color to one lens, as 11,

of'eali lens combination. For example, 11

may be made of green glass, 11 of yellow glass, and ll 'of red glass.These colors are in accordance with standard practicein railwaysignaling and correspond to indications ofprocoed, caution and stop,respectively.

As is well understood in railway signaling practice, the control of thesignal is usually such that as a train passes the signal the lamp 13 islighted and the signal projects a beam of red light to indicate togafollowing train that the block protected by the signal is occupied. Itis frequently desirable that'an observer located on the train should beable to determine that the stop indication is being displayed after thetrain has passed the signal. For this reason I provided a back light forunit B which I will now describe. At-

tached to the frame 15 of'lenses 11 and 12 is a sheet metal member 16carrying a collimating lens 17 so disposed as to project a beamof lightfrom lamp 13 toward the right as viewed in Fig. 2. A housing 18 isattached by means of bolts 18 to the side of shell 2 of unit R. Thishousing is provided with a transparent lass screen or window 19 which isprotected by a hood 20. Immediately inside of window 19 and supportedalso by housing 18 is a reflectordevice D. As best shown in Fig. 5, thisdevice comprises two side rails 21 and 21 and a plurality of transversereflectors 22 fastened at their ends to located side by side and thethird unit located below and equally distant from the other two units,said lamps being adapted for individual illumination and the lenses ofthe three units being distinctively colored, enclosing means for saidunits including a cover for the back of each unit, a Y-shaped spiderhaving one'said cover attached to each leg thereof and means forpivotally attaching said spider to said front plate, the-cover for thelower unit being heavier than the other covers so that said spider isbiased by gravity to a position where in each cover registers with itsassociated unit.

Intestimony whereof I aflix my signature.

CLARENCE S. SNAVELY.

'45 these rails. These reflectors are here shown as strips-of metalhaving their upper surfaces (Fi 5) highly polished. I The signal is soas sem led that the reflector device D is inter- /posed in the beam oflight projected from 50, lamp 13 by collimating lens 17 5 and thereflectors 23 are so disposed that this beam is redirected toward therear of the signal through window 19. The path of this beam is indicatedby the dot-dash lines on Fig. 4.

One surface of window 19 may be frosted or lightly sand-blasted fordiffusing the light from reflector device D. It will be noticed that dueto the angular position of window 19 the condition of energization ofunit R may thus be observed in the rear of the signal,

from the right hand side of the signal as viewed in Fig. 2, or from anypoint between these two positions.

Although I have herein shown and described only one form of light signalemwithin thescope of the append" invention, what

